地下矿山水质分析方法有多种，适用于中等杂质含量水样分析的方法是( )。
A．容积法 B．重量法C．比色法 D．浓度法
参考答案：A
金燕借记卡有卡自助消费白名单的总限额为（）元（含）。
A.5000
B.10000
C.20000
D.30000
When I try to understand () that prevents so many Americans from being as happy as one might expect, it seems to me that there are two causes.
A. why it does
B. what it does
C. what it is
D. why it is
